Currently, the medical decision to provide deep venous thrombosis (DVT) prophylaxis to teenagers with multiple injuries may be based not on evidence, but on whether the ambulance transports them to an adult or pediatric trauma facility. In this proposal, we seek to identify which, if any, young trauma patients may truly benefit from the thromboprophylaxis strategies that have become standard of care in adults. The decision regarding who should receive thromboprophylaxis applies to a large number of patients, with >200,000 pediatric/adolescent trauma admissions every year. However, due to the relative rarity of DVT in young trauma patients, the question is difficult to study by traditional methods. The proposed research involves the construction of a decision analysis model to address the health effects and costs of thromboprophylaxis with low-molecular-weight heparin (LMWH) in pediatric and adolescent trauma patients. Decision analysis models require accurate, unbiased estimates of the various probabilities and outcomes that result from various choices. Currently, there is substantial uncertainty regarding several of the parameters necessary to construct such a model. Therefore, we will first analyze the National Trauma Data Bank, the largest aggregation of pediatric trauma registry data, to more clearly define the overall incidence and risk factors of DVT in young trauma patients, and to define the incidence of DVT in specific cohorts. Data collection on the incidence of major bleeding events with LMWH prophylaxis will take place through four major trauma centers. Finally, we will combine our data with the published literature on thromboembolism in pediatric trauma and construct a decision analysis model to estimate total costs of prevention, treatment, and outcomes of DVT in specific cohorts of pediatric trauma patients. The proposed research will provide clinicians with a tool to identify young trauma patients who would benefit from LMWH prophylaxis. The results will be used to create child and adolescent-specific guidelines, thereby allowing clinicians to maximize patient safety and minimize costs when considering LMWH prophylaxis for a young trauma patient. [unreadable] [unreadable] [unreadable]